Choose Apple menu > System Preferences and click Users & Groups.
Click Change Password.
Enter your current password in the Old Password field.
Enter your new password in the New Password field, and then enter it again in the Verify field.
For help choosing a secure password, click the Key button next to the New Password field.
Enter a hint to help you remember the password. This hint appears if the wrong password is entered three consecutive times in the login window.
Log in to the computer using an administrator name and password.
Choose Apple menu > System Preferences, and click Users & Groups.
Click the lock icon to unlock it, and then enter your administrator name and password.
Select the account whose password you want to change.
Click Reset Password.
Enter a hint to help you remember the password. This hit appears if the wrong password is entered three consecutive times in the login window.
Important: After changing or resetting a password, open Keychain Access and change the “login” keychain to match the new login password. This unlocks the keychain when you log in. For more information, see: Changing your keychain password